Running out of ideas on overheating

[SBpunk]

Have you installed your mechanical temp guage yet?
230 is on the hot end but not uncommon on 90 degree days with the ac on

Yup and wasn't running A/C. About 97 here yesterday and shot up in about 20 mins driving home around town

 

[techno1154]

Did you check the water pump? i.e. is it the correct water pump? Remember, the water pump runs on the back of the belt and rotates in the reverse or anti-clockwise direction. Other identical pumps rotates in a clockwise direction.

That new 3 core radiator, could you verify that water is passing through all the cores? In 2001, I had a brand new radiator like the one you have that caused my XJ to over heat. Some of the tubes were blocked. This was verified buy a simple touch test when the engine was hot and shutdown. There was a large variation in temperature across the tubes of the radiator.

Also, scales that broke loose from the new rebuilt/installed engine could have broken loose and block the radiator especially one with 3 tiny tubes.

 

[Green Mesa XJ]

Something is not circulating correctly . Maybe the the radiator cap, as suggested earlier.
The reservoir should show some signs of expansion when it warms up to damn hot.
Either the cap is blocking expansion to the reservoir, or the radiator is, possibly bad water pump or a engine water port is blocked .

At least that's what comes to my mind.



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[BCKNBLK]

You must be confident that none of the coolant passages in the block are obstructed from the cleaning process before the rebuild, which I have seen happen before as the block is hot-tanked and not all of the scale is removed, it becomes loose and may lodge itself between the cylinder walls, preventing coolant flow. Barring this, make sure that the coolant system has also been purged of air. This is more important than you may think. And also, as mentioned before, use a factory rated thermostat, do not continue using the 180 degree piece, this is too low.

 

[SBpunk]

You must be confident that none of the coolant passages in the block are obstructed from the cleaning process before the rebuild, which I have seen happen before as the block is hot-tanked and not all of the scale is removed, it becomes loose and may lodge itself between the cylinder walls, preventing coolant flow. Barring this, make sure that the coolant system has also been purged of air. This is more important than you may think. And also, as mentioned before, use a factory rated thermostat, do not continue using the 180 degree piece, this is too low.

Not confidant at all about it. Just don't have time to pull the head to check to passages. Once I get some leave I'll take a week and pull it if moving the thermostat back to 195 (got the mopar part) and trying another radiator cap. Spending the long weekend getting my other POS fixed up. Won't ever buy another 4.7 motor.

 

[anderld47]

So last ditch effort (aside from a plastic mopar radiator) is this 195 mopar thermostat and bleeding the back of the system. The mopar thermostat came with some weird valve thing on it. I've heard to just remove it so the hole is always open at the 12 oclock position. Good or not so much? Damn thing cost me 33 bucks so apparently its made from gold and unicorn marrow. Going to test it before installing with an IR gun and a pot of water. Oh and going to take it down and get the system pressure tested after its installed just to make sure I'm not crazy and theres some invisible leak I'm not seeing.

I went through this last year on my 98. Reman engine and everything new in the cooling system. All metal 3 row radiator. It would idle forever in 100 degree heat with no problem, but put under load on a hot day would overheat on the temp gauge. Replaced everything except the radiator. Even twice let it go to the point of boiling over thinking it might be something wrong with the gauge even though I had replaced the sending unit. Removing my winch didn't help.

Had leak down and block test done and both were negative.

I checked the TSBs for my year and I think there were two bulletins on overheating and both involved the catalytic converter.

Finally replaced the all metal 3 core radiator with the OEM (52080104-AC) from a MOPAR parts overstock dealer. As a test I waited for a hot day, put my winch back on, rolled up the windows, turned on the AC, and put my foot into it. Did a 1800ft elevation gain in 6.5 miles on a 100 degree afternoon. The temp needle got to right before the first line above the 210 mark (just a reference point), but never overheated. With the 3 core I couldn't make it 2/3rds of the way on a 85 degree day before the red light and buzzer went off and the needle shot to the highest mark.

So for me, the answer was a $300 OEM radiator.

I guess with 2 1/2 million XJs sold over the years, the OEM cooling system is probably the way to go.

 

[RCP Phx]

Won't ever buy another 4.7 motor.

If it's a 4.7 what have you done about the fuel injectors? Are you sure it's not running lean?

 

[Green XJ Jeep]

Get an ir temp gun and check your radiator for cold spots. Im guessing the tiny tubes on that 3 core either sat dry while the motor was being rebuilt and corroded up a bit or some junk in the motor plugged some up.
Just because its passing water doesnt mean the flow isnt restricted or half the tubes are blocked

 

[Green Mesa XJ]

If it's a 4.7 what have you done about the fuel injectors? Are you sure it's not running lean?

I think he meant the POS had a 4.7 v8. If the new motor is a stoker 4.0 there's another dozen possibilities that might cause overheating .


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[Green Mesa XJ]

Get an ir temp gun and check your radiator for cold spots. Im guessing the tiny tubes on that 3 core either sat dry while the motor was being rebuilt and corroded up a bit or some junk in the motor plugged some up.
Just because its passing water doesnt mean the flow isnt restricted or half the tubes are blocked

I'm forgetting where the radiator comes in this saga, I was under the impression it was new replaced while the engine was rebuilt.
If it's is new and the previous radiator is still around maybe swapping the old one back is an option. If it's not, and since the mopar three row seems unavailable I would either try to warranty the new radiator (if it is new) or just buy another metal 3 row radiator and test it.
It is acting like a clogged radiator if we assume the water ports in the block are clear and the water pump is good.
I still don't understand why the reservoir is not seeing a change with the temperatures.


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[Slimer]

I am going through this exact same thing...

http://www.naxja.org/forum/showthread.php?t=1141297

Here is a video of what my guages do...

https://youtu.be/5guiyEPFnnc

I will probably give the factory radiator a try.

 

[Ecomike]

i know on my renix i get air stuck in the back of the head by the dash temperature sensor. the dash gauge will show over 210 but the ecu reading is 195 ish. or maybe that temp sender is faulty.

Actually on Renix there are three temp sensing locations and devices. The ECU temp sensor in the block in a colder part of the engine, closer to the colder coolant feed IIRC. While the dash gauge temp sensor is in the hottest part of the head near the firewall. The two temps will never be the same except maybe after sitting for a day, LOL.

 

[Ecomike]

I doubt its the condenser since this started from a working AC and cooling system, started just after a motor rebuild.

I'd worry more about the condenser in front of the radiator blocking air flow than trying to find a mopar radiator. Unless you've got a particularly defective aftermarket radiator I don't think mopar radiator will solve the issue. If the fuel mixture and exhaust are correct and the problem is in the cooling system then maybe it'd be worth swapping out the radiator again. I'm still puzzled how it was working fine before the rebuild to suddenly have trouble.






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[Ecomike]

If the new radiator got clogged, the pressure drop may be large enough that the radiator cap is no seeing enough pressure to open?

But I think he needs to verify that the dash gauge is still giving him correct temp data before he does anything else.

Also one red flag for me on post #1 is he removed the heater core valve, so coolant is bypassing the radiator and going through the heater core and back into the engine!!!! And it may be adding a heat load to the AC, that does a feed back and heat growth loop into the cooling system.

Need to try a new cap. Needs to make sure radiator neck is not defective or damaged. The Cap seals in two places. Also the overflow hose must be changed. It sure sounds like a problem.

The engine head noises listed in post 1 need to be addressed!!!!:twak: Is it running too lean needs to verified. Does it have a bent, or bent lifter rods????

Also the base timing must be checked. The ECU can not compensate for a basic valve timing and Cam position/distributor location error. Pull SPlug #1, turn the crank shaft by hand, socket and ratchet till the vibration dampener shows zero degrees advance, then use a light to see if piston 1 is at TDC. Then check to see if the Dizzy rotor is pointing to the #1 location pin on the Dizzy cap or not..... There are write ups on doing this, Google them for the details. The basic timing, timing chain or the dizzy position maybe off enough to cause the engine to run lean

Lastly put a volt meter on the O2 sensor NOW and see if it is reading lean!!!! Google "Ecomike O2 sensor test Jeep" for the how to thread here.

If it is running lean, you are just pissing away time and money trying to cool it!!!!

I'm forgetting where the radiator comes in this saga, I was under the impression it was new replaced while the engine was rebuilt.
If it's is new and the previous radiator is still around maybe swapping the old one back is an option. If it's not, and since the mopar three row seems unavailable I would either try to warranty the new radiator (if it is new) or just buy another metal 3 row radiator and test it.
It is acting like a clogged radiator if we assume the water ports in the block are clear and the water pump is good.
I still don't understand why the reservoir is not seeing a change with the temperatures.


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[Green Mesa XJ]

The OP has done a lot of trouble shooting. I believe he put on a mopar O2 sensor. Not sure if he's tested it with new radiator cap yet.

Because he's done so much trouble shooting I'm thinking it's got to be the radiator or water ports in the engine. Maybe bad water pump.


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[Ecomike]

Replacing parts is NOT Troubleshooting. It is taking shorts in the dark at a dart board. :laugh3:

Testing the O2 sensor voltage or scanning it with a real scanner to see if it is closed loop and or if it is running lean with test (troubleshooting) equipment is troubleshooting.

I just read the whole thread, he has not yet confirmed if he has even done a second test with an infrared tester at the T-stat housing to confirm that the dash gauge temps are even correct. He could have a sensor ground issue caused by moving the harness around in the engine swap or something like that.

I chased my tail for 3 years on mine. The problem vanished when I replaced the donut in the exhaust manifold outlet flange. A $2 part. :twak:

It escaped three muffler shop inspections. Only leaked under load on the freeway blowing exhaust gasses on the block 1/2" from the Exh Pipe flange. The old donut had been reused by the PO when it should have been tossed.

The OP has done a lot of trouble shooting. I believe he put on a mopar O2 sensor. Not sure if he's tested it with new radiator cap yet.

Because he's done so much trouble shooting I'm thinking it's got to be the radiator or water ports in the engine. Maybe bad water pump.


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[SBpunk]

Replacing parts is NOT Troubleshooting. It is taking shorts in the dark at a dart board. :laugh3:

Testing the O2 sensor voltage or scanning it with a real scanner to see if it is closed loop and or if it is running lean with test (troubleshooting) equipment is troubleshooting.

I just read the whole thread, he has not yet confirmed if he has even done a second test with an infrared tester at the T-stat housing to confirm that the dash gauge temps are even correct. He could have a sensor ground issue caused by moving the harness around in the engine swap or something like that.

I chased my tail for 3 years on mine. The problem vanished when I replaced the donut in the exhaust manifold outlet flange. A $2 part. :twak:

It escaped three muffler shop inspections. Only leaked under load on the freeway blowing exhaust gasses on the block 1/2" from the Exh Pipe flange. The old donut had been reused by the PO when it should have been tossed.

Unfortunately we don't have a harbor freight where I'm at and Amazon took its time sending me the IR scanner. Spent the entire weekend replacing a knock sensor on my 4.7 HO. That turned into replacing valve covers and a few other things since the top of the motor was damn near pulled out.

I'm going to test the new O2 sensor with voltage tool this week. Also putting a 195 thermostat back in, replacing the overflow bottle since its pretty bad and flushing the system/heater core once my 134 A/C conversion stuff gets in.

The exhaust is sealed up tight. One of the first things I looked for was a leak at the downpipe since it had happened when I first swapped it out. That little flange piece you're talking about was left out by the idiot owner (me). Buddy at the Firestone fogged both my jeeps. Only found leaks in my 2004 WJ.

Going to take the IR sensor to the radiator, thermostat housing and fuel injectors. Someone told me if they're not firing properly an injector wont be a cool as the surrounding ones. Running lean could be causing the motor to over heat. I'm going to do another leak down test also just to double check the head gasket. Luckily its a 3 day work week so I should be able to get to most of this by the weekend.

 

[Warlock1]

By the way, the Mopar part number I gave you is the Max Cool radiator, I didn't specify before.

Where's the popcorn smiley? Lol. I'm waiting for the inevitable.

Been there, done that, have the scars and T shirt........

 

[old_man]

Haven't reread the whole post but did the water pump get replaced recently? The pump from the early Renix 2.5L looks identical but has the impeller reversed and can cause a ton of issues. They sometimes get switched at a rebuilder.

 

[techno1154]

Haven't reread the whole post but did the water pump get replaced recently? The pump from the early Renix 2.5L looks identical but has the impeller reversed and can cause a ton of issues. They sometimes get switched at a rebuilder.

Funny, I did mention that in post 42 but got no reply. The engine/block is of unknown condition. The add on cooling system parts,...where did they come from?

It seem the OP is throwing parts at it hoping that the problem will eventually go away. At this point, some methodical trouble shooting is should be done.